Facelina olivacea is a species of sea slug, a nudibranch, a marine gastropod mollusc in the family Facelinidae. This distinctive species is known for its vibrant coloration and elongated body form, which distinguishes it within its genus.
Description & Characteristics
Facelina olivacea is characterized by its slender, elongated body, typically reaching a maximum length of 25 millimeters. The body of Facelina olivacea is often translucent, revealing a bright yellow or orange internal gut. The dorsal surface of the body is adorned with numerous cerata, finger-like projections that extend from the body’s sides, giving the slug a feathery appearance. These cerata, which are the most prominent features of Facelina olivacea, are typically white or cream-colored, sometimes tipped with orange. The cerata are not only for display, but also serve a vital function for Facelina olivacea by housing defensive nematocysts stolen from its prey, hydroids.
Habitat and Occurrence
Facelina olivacea is found in the coastal waters of the northeastern Atlantic Ocean, where it primarily inhabits shallow, rocky intertidal zones. It is a common species in this habitat, often found amongst algae and other invertebrates. This species has also been reported in the Mediterranean Sea, further expanding its geographical range. It is predominantly found in the infralittoral zone, extending from the low tide mark to depths of around 20 meters.
Taxonomy
Facelina olivacea belongs to the Class Gastropoda, which comprises a vast and diverse group of mollusks, encompassing snails, slugs, and other related organisms. Within this class, Facelina olivacea falls under the Order Nudibranchia, a specialized group of sea slugs that lack external shells and often exhibit striking colors and patterns. Finally, Facelina olivacea is a member of the Family Facelinidae, a family of nudibranchs that are characterized by their slender bodies and numerous cerata.
Feeding
Facelina olivacea is a carnivorous species, feeding primarily on hydroids, a type of colonial marine animal. These hydroids often house stinging cells called nematocysts, which Facelina olivacea skillfully extracts and stores within its own cerata for defense. This remarkable adaptation allows Facelina olivacea to benefit from the hydroids’ defensive weaponry, making it a formidable predator in its environment.
Image References